1. Field of the Invention
The present invention relates to a gas compressor to be used with a car cooler or air conditioner and, more particularly, to a gas compressor in which the volume of its compression chamber is made variable.
2. Description of the Prior Art
Usually, a gas compressor to be used for cooling the automobile or the like is arranged in parallel with an engine so that it may be driven through a V-belt by the crankshaft pulley of the engine, and it is connected to or disconnected from the driving force by means of an electromagnetic clutch which is disposed on the compressor side.
As a result, the volume of the gas compressor of the above-specified type is increased in proportion to the r.p.m. of the engine. This in turn causes the gas compressor to be driven at a high speed, in case the automobile runs at a high speed, thereby to relatively overcool the automobile compartment and to raise the shortcoming that the power consumption is also increased in proportion to the running speed. This tendency is serious especially in a gas compressor of the rotary type.
In order to eliminate this defect,there have been proposed a variety of the so-called "volume-variable type" gas compressors in which the volume of the compression chamber for the coolant gas is varied in accordance of the compressor the driving speed thereof.
For example, the volume of the compression chamber can be made variable by controlling the opening of a bypass hole, which is formed in a position suitably displaced in the rotational direction of a rotor with respect to an intake port.
In the gas compressor of this type, the coolant gas, once confined in the compression chamber, is bypassed to an intake side after it has been compressed to some extent. Therefore, such a gas compressor has been noted to have an inferior compression efficiency and the drawback that the discharge temperature of the coolant gas rises especially at highspeed, i.e., small-volume run.
To overcome these shortcomings the gas intake compressor developed in recent years is of the type in which the intake capacity to be sucked in from an intake port of a front side block of the compressor is made variable by using a rotary plate as the front side plate, by forming this rotary plate with a recess communicating with the intake port, and by rotating the rotary plate a predetermined angle. In the gas compressors as developed, most have a means for controlling the rotary plate that are constructed such that the temperature of the air to be blown out of the automobile compartment or an evaporator is sensed by means of a thermostat so that the rotary plate may be turned by the drive of a motor attached to the compressor when the temperature drops to, or lower than, a set level of the thermostat. This raises certain defects in that the construction is complicated and large-sized due to the motor which is added.
For example, in U.S. Pat. No. 4,137,018, it is disclosed that a control plate is mounted between a cylinder and a front side block, and that the shaft 220 which gears with the control plate 200 (in the patent) drives the control plate 200. In this mechanism, however, another drive means for driving shaft 220 is required. It is not specifically described in the specification that this mechanism is controlled automatically. Provided that the control plate 200 is controlled automatically, the mechanism will be complicated on the whole, and will not be simplified and compact.